This invention relates to a fluid-cooled member. More particularly, it relates to a water-cooled electrode holder.
In the past, water-cooled electrode holders have generally been made in one of two ways. First, cooling coils, made of Monel, for example, have been embedded directly in a copper casting. However, shrinkage of the casting during solidification resulted in areas of relatively poor contact between the cooling coils and the copper. Hence, the thermal conductivity between the coils and the casting was poor at these areas, and the cooling effectiveness of the coils was consequently less than satisfactory.
A second method of producing such a holder comprised casting the copper holder with the recesses already formed in them. It was found, however, that such holders were unsatisfactory for several reasons. First, if the grains of the casting were excessively large, which was not at all unusual, the coolant was likely to leak directly through the grain boundaries. In addition, such castings were frequently characterized by excessive porosity, which permitted coolant to pass directly to the surface of the casting through connected passages formed by air bubbles leaving the casting during solidification. Furthermore, such castings frequently cracked during service as a result of the heat generated by the large currents supplied to the electrodes.
More recently, electrode holders have been formed by welding an outer plate to a casting and providing arcuate inner plates between this outer plate and the casting to form passageways for the flow of coolant within the holder. However, there is no way to weld these inner plates to both the casting and the outer plate. Thus, inasmuch as the outer plate inevitably warps as a result of the continuous heating and cooling of the holder, considerable space develops between the edges of these inner plates and the walls they extend between. This results in poor definition of cooling paths and consequent ineffective cooling.
It is an object of this invention to provide a fluid-cooled member that is characterized by a high degree of cooling effectiveness.
It is a more specific object of this invention to provide such a member that forms part of an electrode holder.